In March 2009, in Century City, Calif., four months after California voters passed Proposition 8 to ban same-sex marriage, political consultant Chad Griffin stood in a crowd of veteran gay activists and reeled from the hostility in the room. The ire was directed at the man onstage, screenwriter Dustin Lance Black, who had recently won an Oscar for Milk, about the gay activist Harvey Milk, who was assassinated in San Francisco in 1978.

Like Griffin, Black was in his mid-30s and gay. Both men felt that the movement for marriage equality had lost its momentum. Hoping to jump-start it, they showed up at a biannual event that draws high-end donors to political and charitable causes for the gay community. Their goal was to drum up support for a federal lawsuit challenging Prop 8.

Black had made clear his dream in his Oscar acceptance speech, when he directly addressed struggling gay and lesbian kids: “No matter what everyone tells you, God does love you, and . . . very soon, I promise you, you will have equal rights federally across this great nation of ours.”

Those were fighting words for 52-year-old Evan Wolfson, the primary force behind the plodding, state-by-state strategy for gay marriage. He had cornered Black hours before he took the Century City stage, fuming over his Oscar speech and the young man’s restless ambition. Who was Black, Wolfson demanded, to tell those who’d been in the trenches for decades how to fight this battle?

In her new book, Forcing the Spring, Jo Becker, a former Monitor and Washington Post reporter now with the New York Times, uses this standoff to foreshadow deep divisions that threatened to derail a movement that had yet to begin.

Black was shaken by Wolfson’s rebuke but undeterred. He took the stage and beseeched the room full of activists to join a renewed battle for their rights: “The strategy of the past has failed. We have lost state and local fights time and again. . . . It is time for us to stop asking for crumbs and demand the real thing.”

Black walked off the stage and into “an ocean of pursed lips and crossed arms.” One of the largest funders of gay causes in the United States “denounced Black outright, telling the crowd he was naive and misguided.”

Griffin was shocked. He had been working with director Rob Reiner and his wife, Michele, and other Hollywood giants to form a bipartisan legal team to challenge Proposition 8 in federal court. Doing so, they hoped, would force the U.S. Supreme Court to rule on same-sex marriage. As Becker notes in her book, “No group in America had been targeted by ballot initiatives more than gays and lesbians.” Of the roughly 200 such contests since the 1970s, they had lost 70 percent. When the contest involved marriage or adoption, they lost every time.

So much for a state-by-state legislative strategy that promised a continued delay of years, if not decades.

Griffin knew from the outset that conservatives would fight them. As he was quickly learning, so would many prominent gay activists. “Oh my god,” he said to Black. “We are going to be loathed and hated. How are we going to sell this?”

“Sell” is the operative word, for that is what the plaintiffs’ team did over the next five years, legally and through a meticulously executed public relations campaign.

Becker launches Forcing the Spring with a bold claim: “This is how a revolution begins.” She then proceeds to illustrate with the deftest of prose the delicate balance that had to exist between patience for process and an insistence on now.

This book is not intended to be a tome on gay history, but Becker should brace for accusations of omission, particularly by longtime activists who will feel marginalized. Forcing the Spring is a riveting legal drama, a snapshot in time, when the gay rights movement altered course and public opinion shifted with the speed of a bullet train.

Sometimes the plaintiffs in the case brought to have Proposition 8 declared unconstitutional got lucky.

Attorney Chuck Cooper, for example, stumbled into the perfect sound bite after U.S. District Judge Vaughn Walker pressed him to explain how same-sex marriage harms “marriage for procreative purpose.”

Mostly, though, the plaintiffs outhustled and, over time, overwhelmed the opposition, in court and in public opinion. Nothing was left to chance, and virtually all of it is chronicled by Becker, who nailed down a reporter’s dream of an agreement: four years of “complete and unfettered access” to the plaintiffs and their legal team.

The hundreds of delicious details in this book lay bare Becker’s gift for coaxing information out of even the most reticent subjects. And although she also tried to interview major players on the defendants’ side after the legal battle, the book is lopsided because there is only so much that defeated lawyers want to share about losing strategies. Still, she resists the heavy-handedness of a cheerleader.

She also forces even the most ardent supporters of same-sex marriage, and I am one of them, to consider a more nuanced view of some members of the opposition. Many of them did not approve of Prop 8 literature that warned parents that gay marriage would lead to sex with children. Some would have been willing to accept civil unions.

There are a few touching moments when conservatives who publicly proclaim the sanctity of traditional marriage privately confide to Becker their inner conflicts born of tender feelings toward the plaintiffs or toward members of their own families. It’s an effort at balance, bound to make some supporters on either side uncomfortable.

Becker’s most remarkable accomplishment is to weave a spellbinder of a tale that, despite a finale reported around the world, manages to keep readers gripped until the very end. In part, this is because litigation is only part of the story.

The plaintiffs’ team – led by two lawyers who were on opposite sides in Bush v. Gore, Republican Ted Olson and Democrat David Boies – wanted Proposition 8 ruled unconstitutional.

But as the case made its way through the federal court system, they had another goal: “to flip public opinion on same sex-marriage to majority support by the time the case reached the U.S. Supreme Court, in the hope that a more hospitable political climate would make the justices feel more comfortable ruling their way.”

To this end, nothing was left to chance, from the “packaging” of the four plaintiffs to a persistent and ultimately successful campaign to persuade President Obama to change from “evolving” on the issue of same-sex marriage to supporting it.

Joe Biden takes a star turn as the irrepressible vice president who calmly, and oh-so-publicly, mentions his support.

Becker’s command of the law is essential to her deconstruction of complex arguments and insights into what led the jurists – from Walker, the gay federal judge who overturned Proposition 8 at the trial level, to the members of the Supreme Court – to their conclusions. At every step, she offers poignant reminders of the utter humanity of all the players.

After the Los Angeles Times reported that Chief Justice John Roberts’s lesbian cousin, who longed to marry her partner, would be in the courtroom, lawyers warned the plaintiffs and their supporters not to mention it. One of the plaintiffs posted a link to the story on Facebook but then removed it at the lawyers’ urging. “We are allowed to be secretly thrilled,” Democratic consultant Hilary Rosen emailed.

While the case, Hollingsworth v. Perry, made its way to the Supreme Court – which in 2013 let stand previous rulings that said the law was unconstitutional – public opinion shifted, as Cooper put it, “with a velocity unlike anything I have ever seen.” The first national poll to show majority support for same-sex marriage came out only weeks after the district court victory.

Former Republican National Committee chairman Ken Mehlman, who had recently come out as gay, joined the effort.

So did former defense witness David Blankenhorn, who wrote about his change of heart for the New York Times: “If fighting gay marriage was going to help marriage over all, I think we’d have seen some signs of it by now.”

“This battle . . . is over,” he said elsewhere. “It’s over. People have made up their minds. It’s just a huge mopping up at this point.”

While this is a book about victories, big and small, at its core it’s the story of the pain harbored in the hearts of gay adults who yearn to be free of the demons of the past. It’s the story of plaintiff Kris, who testified how she went to great lengths “to develop other traits that people do like.”

It’s the story of Ryan Kendall, who testified at trial that his mother once told him she wished she’d had an abortion rather than give birth to a gay son. It’s the story of Cleve Jones, too, who prayed every night as a child, “Please, God, fix me.”